Elephant Jungle Sanctuary - highly recommend!
View from the hotel hammock - Hotel Renaissance
Playing tourist on James Bond Island - in the bay of Phang Nga
I loved visiting Phuket, it was a true tropical holiday and the elephant sanctuary was a fantastic place to visit. A lot of people still don't know how bad riding the elephants is, and this sanctuary really teaches you what the elephants need and tells you some of their stories of how they came to be in the sanctuary and the places they were rescued from (eg riding, logging and the circus). You also get to feed them, and even join them for a mud bath which was an experience I will never forget.
We also did a couple of boat trips with the Seastar company, and they were very well staffed with snacks and refreshments throughout the trip plus of course lunch. The islands we got to tour were spectacular, and the staff was very knowledgeable as what is best to see based on the weather conditions, so be prepared to have it altered (but it's worth it). One day we did Phi phi islands and the other we visited James Bond Island along with a floating village (and the best part, kayaking in a lagoon area!).
On every trip, you also need a good hotel day and we had some of those too which was perfect as our hotel was very quiet and secluded. If you aren't looking to be in the town and near all the hustle and bustle, then I would definitely recommend the Renaissance hotel. They have restaurants, and even great room service along with being right on the beach.
Now we did go in Monsoon season, so the recommended time to visit is more November to February but we got very lucky and it really only rained at night or for very short periods of time during the day (and always when we were on route in the boat or in the car, or at the hotel). You may not get that lucky, so it's good to be aware of this. However, it is still super warm so that isn't an issue!
Let me know if you have visited any of these before.